ASSESSMENT OF ACUTE PARATHYROID RESPONSIVENESS TO HIGH-CALCIUM DIALYSATE IN UREMIC PATIENTS

The response of the parathyroid glands to dialysis-induced changes in calcium has been studied in 83 normocalcemic patients receiving mainte nance hemodialysis. Predialysis concentrations of intact parathyroid h ormone (iPTH) were normal in 13 patients; 70 patients had increased iP TH levels of different degrees. All patients had analytically signific ant changes in total serum calcium (2.3 +/- 0.2 vs 2.8 +/- 0.2 mmol/l) without additional parenteral calcium loading during a standard dialy sis session with a dialysis solution of 1.75 mmol calcium chloride. Du ring hemodialysis the concentration of IPTH fell in 77 patients and wa s normalized in 48 of these patients. The remaining 6 patients showed no or an inadequate response (less than 30% suppression of predialysis iPTH) to the increase in Ca. Parathyroidectomy was performed in patie nts with refractory IPTH secretion. Histological evidence of marked pa rathyroid hyperplasia was obtained in all these patients. All patients with normal or partial responsiveness of the parathyroids tolerated a t least small doses of -1.25 (OH)(2)-vitamin D-3. Quantification of pr edialysis and postdialysis IPTH concentrations is a useful and simple method for identifying those uremic patients with true autonomy of the parathyroid glands at an early stage.